CHEM 210 Module 2 Exam Newest
1. a higher melting or boiling point indicates the molecule has: stronger inter-
molecular forces.
2. What is the shape of water?: Bent. The bond angle is 104.5 degrees.
3. What is autoionization, and how is it important for water?: Autoionization is
the ability of a compound to react with itself to form ions. One water molecule reacts
with a second molecule to form two ions: H3O+ and OH-. These ions exist in small
amounts in pure water and influence the chemistry of water.
4. Name the three non-covalent forces discussed in this module.: 1. Dipole-di-
pole forces, 2. Hydrogen bonding, and 3. London dispersion forces
5. What type of non-covalent interaction is known as the strongest dipole-di-
pole force?: hydrogen bonds
6. How does the strength of London forces change with increasing molecular
weight? Explain briefly.: As molecular weight increase, the strength of London
forces also increase. This is due to the increased number of electrons in larger mol-
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, ecules. The larger number of electrons creates the potential of stronger temporary
dipoles.
7. What is the concentration, in M, of water as a pure liquid?: 55.5 M
8. Define Keq and Kw.: Keq is the equilibrium constant. Numerically, it is equal
to the concentrations of equilibrium products (in M) multiplied together over the
concentration of equilibrium reactants multiplied together.
Kw is called the ion product. It is, essentially, the Keq for water that is equal to 1.0 x
10-14; the formula is:
9. Identify the acid, conjugate base, and proton in the following reaction.
HCOOH --> H+ + HCOO-: HCOOH weak acid
H+ proton
HCOO- conjugate base
10. A buffer system has a pKa of 8.5. What is its effective buffering range?: 7.5
to 9.5
11. Weak acid A has a pKa of 3.2, while weak acid B has a pKa of 5.6. Is Weak
acid A or B the stronger of the two?: Weak acid A is stronger because a smaller
pKa indicates a stronger acid.
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1. a higher melting or boiling point indicates the molecule has: stronger inter-
molecular forces.
2. What is the shape of water?: Bent. The bond angle is 104.5 degrees.
3. What is autoionization, and how is it important for water?: Autoionization is
the ability of a compound to react with itself to form ions. One water molecule reacts
with a second molecule to form two ions: H3O+ and OH-. These ions exist in small
amounts in pure water and influence the chemistry of water.
4. Name the three non-covalent forces discussed in this module.: 1. Dipole-di-
pole forces, 2. Hydrogen bonding, and 3. London dispersion forces
5. What type of non-covalent interaction is known as the strongest dipole-di-
pole force?: hydrogen bonds
6. How does the strength of London forces change with increasing molecular
weight? Explain briefly.: As molecular weight increase, the strength of London
forces also increase. This is due to the increased number of electrons in larger mol-
1/4
, ecules. The larger number of electrons creates the potential of stronger temporary
dipoles.
7. What is the concentration, in M, of water as a pure liquid?: 55.5 M
8. Define Keq and Kw.: Keq is the equilibrium constant. Numerically, it is equal
to the concentrations of equilibrium products (in M) multiplied together over the
concentration of equilibrium reactants multiplied together.
Kw is called the ion product. It is, essentially, the Keq for water that is equal to 1.0 x
10-14; the formula is:
9. Identify the acid, conjugate base, and proton in the following reaction.
HCOOH --> H+ + HCOO-: HCOOH weak acid
H+ proton
HCOO- conjugate base
10. A buffer system has a pKa of 8.5. What is its effective buffering range?: 7.5
to 9.5
11. Weak acid A has a pKa of 3.2, while weak acid B has a pKa of 5.6. Is Weak
acid A or B the stronger of the two?: Weak acid A is stronger because a smaller
pKa indicates a stronger acid.
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